Pulverized-fuel-burning apparatus



S. G. DOWN AND C. D. STEWART. PULVERIZED FUEL BURNING APPARAIUS- APPLICATION FILED OCT. I5, 1918.

1,388,030. Patented Aug. 16 1921.

2 SHEETSSHEET i.

CARLTON D. STEWART I 3 g I '3 f F &

g3 v A 5 J 1' INVENTORS g, SIDNEY G. Down s. G. DOWN AND c. n. STEWART. 'PULVERIZED FUEL BURNING APPARATUS.

APPLICATION FILED OCT. I5, 1918. 1,388,036. PatentedAug. 16,1921.

2 SHEETS-SHEET 2 myEN'roR's SIDNEY 6 Down CARLTON D.STEwART invention; Fig.

i e e away; Fig. 3 a central sectional view of the SIDNEY Gr. DOWN AND CARLTON I). STEWART, 0F BERKELEY, GALIFORNI EA.

PULVERIZED-FUEL-BURNING APPARATUS.

Application filed To all whom it'may concern:

Be it known that we, SIDNEY G. DOWN and CARLTON D. STEWART, citizens of the United States, residents of Berkeley, in the county of Alameda and State of California, have jointly invented certain new and useful Improvements in Pulverized-Fuel- Burning Apparatus, of which the following is a specification.

This invention relates to apparatus for controlling the burning of fuel, and more particularly to an apparatus adapted to handle pulverized or powdered fuel.

One object of our invention is to provide means for automatically regulating the fires under one or more boilers, by varying the quantity of fuel supplied, the rate of fiow of the fuel distributing medium, and the degree of draft, in accordance with fluctuations in steam boiler pressure.

Another object of our invention is to provide means for adjusting the relative rates of flow of fuel, fuel distributing medium, and air to the furnace, so as to secure the most perfect combustion and highest efficiency, independently of the automatic regulating means.

Another object is to provide means for controlling the flow of fuel, distributing medium, and the draft by steps, and means for each step to provide a predetermined rate of How of each element.

Still another object of the invention is to provide a fire regulating apparatus adapted to be controlled in accordance with variations in steam pressure direct from the boiler, from the throttle pipe which supplies steam from the boiler to the engine, by variations in the degree of vacuum in the smoke] 'box of the boiler, or by a combina tion of steam pressure and vacuum.

Other objects and advantages will appear in the following more detailed description of our invention.

In the accompanying drawings; Figure 1 is a diagrammatic side elevation, partly in section, of a fire controlling apparatus applied to a steam boiler and embodying our 2 an end elevation of the apparatus shown in Fig. 1 with parts broken master controller; and Fig. 4 a sectional View of a portion of the master controller,

Specification of Letters Patent.

showing amodified method of operating the controller.

Referring to Figs. 1 and 2 of the drawings, the regulating apparatus may comprise a fuel supply pipe 1, leading into an air supply pipe 2, which connects with the furnace or fire box of boiler 3.

Fuel may be supplied to pipe 1 by means of a screw conveyer 4, having a hopper 5 and a gate 6 for controlling the supply of fuel from the hopper to the screw conveyer.

Air for distributing the fuel into the furnace is supplied through pipe 7 and a suitable nozzle 8 to pipe 1 and is controlled by a valve 71 in the pipe 7 adapted to be operated by an arm 9, operatively connected to an arm 72 on a main shaft 10.

For supplying air to the air supply pipe 2 and the fuel distributing medium pipe 7, a rotary blower 11 is provided and the shaft 12 of the blower may be operated by an electric motor 13. On the blower shaft 12 is a pulley 14 in line with a pulley 15 on the shaft 16 of the screw conveyer 4, so thatthe conveyer may be operated by the motor 13, through belt 17.

A rheostat 18 is. provided for regulating the speed of the motor 13, the switch arm 19 of which is operatively connected to an arm 73 on the shaft 10.

In order to operate the main shaft 10, a master controller 20 is provided, comprising a casing having piston chambers 21 and 22 containing therespective pistons 23 and 24.

Patented Aug. 16-, 1921. October 15, 1918. Serial No. 258,142.

The respective piston stems 25 and 26 of 24 are connected by an equalizing link 27, which is pivotally connected to a rod 28 for operating an arm 29 carried by the shaft 10.

The chambers below the pistons 23 'and 24 are supplied with fluid under pressure through pipe 30 from any desired source, such as the steam boiler 3. Within the chambers above the pistons 23 and 24 are valves 31 and 32 for controlling the exhaust of fluid pressure from said chambers through a common passage 33 to an exhaust pipe 34. i

For operating the valves 31 and 32 a flexible diaphragm 36 is mounted in the upper part of the casing of the controller 20, the diaphragm being subject on one side to the pistons 23 and steam pressure supplied from boiler 3 through pipe 37 and on the opposite side to the pressure of a spring 38, which may be adjusted to the desired pressure by means of an adjusting nut 39.

The diaphragm 36 is connected to a rod 40 having at its lower end a cross arm 41 carrying adjustable tappet screws 42 and 43 adapted to engage the respective projecting stems 44 and 45 of the valves 31 and 32. lVhen the valves 31 and 32 are not acted upon by the tappet screws 42 and 43, they are held seated by the respective springs 46 and 47.

The pressure in the chamber above piston 24 is also controlled by an auxiliary valve 48 adapted to be operated by a diaphragm 49, subject on one side to a spring 50, and according to one method of control, the opposite side of the diaphragm may be open to the atmosphere through passage 51, while the spring side of the diaphragm is connected by pipe 52 to a vacuum source, such as the smoke box 53 of the boiler 3.

The stack damper 54 is connected through an arm 55, rod 56 and arm 57 to shaft 10, while the furnace draft door 58 is ada )ted to be operated from shaft 10 through a c ain 59 adapted to wind on a pulley 60 carried by said shaft.

A valve 74 in the air pipe 2 is operated from the shaft 10 through an arm 61, rod 62, and arm 63 carried by the shaft.

The main shaft 10 is also provided with a counter-weight 64, which tends to maintain the pistons 23 and 24 in their lower positions. p

The various lever arms on the shaft 10 are adapted to be adjusted angularly to suit the desired conditions as to the control of the elements of combustion and the draft.

Before describing the operation of the apparatus, it may be stated that the parts are adjusted to providethe proper regulation of the fire necessary for forced draft as distinguished from natural draft, and, as shown in Fig. 1 of the drawings, forced draft may be produced by connecting the throttle pipe 68, through which steam is supplied to the engine or other steam user, to the smoke box 53 by means ofa pipe 70. It will now be seen that when the usual throttle valve 69 is opened to admit steam to the engine, steam is also supplied through the pipe 70 to the smoke box 53. A partial vacuum is thus created in the smoke box in the well known way which then causes a forced draft by inducing a flow of atmospheric air through the fire box by reason of the higher pressure of the atmospheric air on the outside.

In operation, if the steam boiler pressure acting on diaphragm 36 of the master controller 20 is less than the reactive force of the spring 38, the diaphragm will be held in its upper position, as shown in Fig. 3 of the drawings, and the valves 31 and 32 will be held seated by the respective springs 46 and 47. The pipe 30 being connected to a source of fluid pressure, such as the steam boiler 3, fluid pressure, admitted to the chambers below the pistons 23 and 24, will equalize through the respective equalizing ports 65 and 66, in the pistons 23 and 24, to the chambers above the pistons, and the fluid pressures on opposite sides of the pistons being thus equalized, the pistons will remain in their lower positions under the action of the counter-weight 64.

According to the method of control now being described, the port 51 of the auxiliary valve device is open to the atmosphere, while pipe 52 is connected to the smoke chamber 53 of the boiler 3. Assuming that at this time the fire is subjected to forced draft, a partial vacuum will be created in the smoke box and in the spring chamber below the diaphragm 49 through the inductive action of the steam supplied to the smoke stack, so that the atmospheric pressure acting above the diaphragm will overcome the reactive force of the spring 50, and the valve 48 will therefore be held to its seat.

In the lowermost position of the pistons 23 and 24, the shaft 10 is in position such that lever arm 19 cuts out the rheostatic resistance in the motor circuit and permits the motor 13 to run at a high rate of speed.

The blower 11 is therefore operated at high speed, as well as the conveyer 4. The valve in pipe? operated by lever 9 is now in position for permitting air under pressure to flow at the desired rate through nozzle 8 and combines with the pulverized fuel supplied by the conveyer 4, the fuel and air be ing then supplied through pipe 1 to the boiler furnace. The lever arm 61 is also in a position for opening the valve in air pipe 2, so as to permit the desired relative flow of air through this pipe to the furnace.

The lever 55 is also held in position for maintaining the stack damper 54 in its open position and the furnace draft door 58 is similarly held in its open position.

Under the conditions described above, it will be evident that furnace fires will burn as freely and intensely as possible.

When the steam boiler pressure has been increased to a predetermined degree, according to the adjustment of the spring 40, the diaphragm 36 of the master controller 20 will be operated by the steam pressure, forcing the cross arm 41 downwardly.

The tappets 42 and 43 are adjusted so that the tappet 43 will engage the valve stem 45 in advance of the engagement of tappet 42 with the valve stem 44, So that the valve 32 is first opened by the movement of cross arm 41. Fluid in the chamber above piston 24 is then vented to the pipe 34 at a greater rate than fluid can equalize through port 66, H

withthe result that the higher pressure below piston 24 operates to lift said piston and cause a'movement of the link 27. This movement of the link 27 is transmitted through rod 28 and lever 29 to shaft 10, which is thenrotated a certain amount, causing the has lever 19 of the rheostat to cut resistance into the motor circuit. The speed of the motor 13 is then reduced, and consequently the speed of the blower 11 and the conveyer 4. The valve 71 in pipe 7 operated by lever9, and the valve 74 operated by lever 61 are also partly closed to reduce the flow of fuel distributing medium and air. The damper 54 and the draft door 58 are also turned to a partially closed position.

The above described setting provides for a moderate fire under the boiler, by reducing the rate of flow of fuel and the amount of draft.

If the boiler pressure should continue to' increase, in spite of the reduced fire, the diaphragm 36 will continue its downward movement, so as to cause the tappet 42 to engage the valve stem 44 and open the valve 31.

Fluid under pressure in the chamber above piston23 will now be vented to the exhaust pipe 34, causing the pressure below the piston 23 to lift the piston and thus eflect a further upward movement of the link 27 and the rod 28.

The shaft 10 is therefore rotated to a fur ther extent, causing the rheostat lever 19 to move so as to cut more resistance into the motor circuit, and thus further decrease the speed of the motor 13, the blower 11. and the conveyer 4.

The valves 71 and 74 in pipes 7 and 2 are also operated to still further reduce the flow of fuel distributing medium and air and the damper 54 and the draft door 58 are further closed.

The setting is now such that only a small fire is provided for. the parts being in the positions shown in Figs. 1 and 2.

If the boiler steam pressure should now become reduced, the diaphragm 36 will be moved upwardly by the spring 40, first permitting the valve 31 to seat.

Fluid pressures on opposite sides of piston 23, will now equalize through port 65, permitting the piston.23 to be moved to its lower position by the action of the counterweight 64.

The shaft 10 is therefore rotated, so as to cause the rheostat arm 19to cut out resistance from the motor circuit, which, as will be evident. causes a speeding up of the motor the blower 11 and the conveyer 4, as well as an opening of the valves in pipes 7 and 2 and the partial opening of the damper .34 and the furnace door 58, so that the fire is increased over the minimum previously existing.

- the fire.

to close, and the fluid pressures to equalize on opposite sides of piston 24.

The piston 24 is then moved to its lowermost position by the action of the counterweight 64 and the shaft 10 is turned, so as to operate the lever 19 to cut more resistance out of the motor circuit, thereby increasing the speed of the motor and the speed of the blower 11 and the conveyer 4.

The levers 9 and 61 are also operated by the shaft 10 to further open the valves in the pipes 7 and 2, and the damper 54 and the draft door 58 are likewise moved to more open positions.

The setting above described now provides for a large fire in the boiler furnace.

In the above description, a complete cycle of operation from a large fire to a small fire A still further decrease in boiler steam and from a small fire to a, large fire is cov- 'the fire must be reduced, regardless of the steam pressure present in the boiler.

According to the operation, as so far described, the use of a forced draft was assumed, and this produced a suflicient vacuum in the smoke box to operate'the diaphragm 49' of the auxiliary controlling device so as to hold thevalve 48 closed.

lVhere, however, the forced draft is shut Y artial vacuum unoff from the boiler, the der the diaphragm 49 will be reduced sufficiently to permit the spring 50 tomove the diaphragm 49 and thus open the valve 48.

Fluid will then be vented from the chamber above piston 24, so that said piston is operated by the pressure below the piston to lift the link 27 and operate rod 28 to turn the shaft 10.-

-Thus the regulating with the shaft 10 is operated as in the case hereinbefore described, by the lifting of piston 24. to reduce the intensity of the fire.

It will now be seen that the supply of fuel; air, and the draft to the furnace will be reduced by the change in the vacuum of the smoke box, Without any change having taken place in the steam pressure of the boiler.

If the forced draft should again be applied. to the boiler, the increase in vacuum thus produced will again cause the closure of valve 48 and the return of piston 24 to its lowermostposition, thus operating the regulating mechanism to increase the intensity of Under certain conditions of operation, when forced draft by induction effected mechanism connected through the use of exhaust steam from the engine, instead of by means of live steam as hereinbefore described in the specification and shown in Fig, l of the drawings, the auxiliary device may be arranged as shown in Fig. 4: of the drawings, with a pipe 67 connected to port 51 and leading to the throttle pipe 68 which supplies steam to the engine, and with the port leading to the pipe 52 open to the atmosphere.

With this arrangement, when the throttle 69 is open, supplying steam to the engine, steam will also be admitted to the chamber above the diaphragm 49, so that the valve -18 will be held closed to provide the increased intensity of fire, as in the case where the valve is held closed by the operation of the partial vacuum produced in the smoke box.

The range in steam pressure between the different steps of control can be increased or diminished, as desired, by adjusting the tappets 42 and 43, as the tappets can thus be set to come into contact with the valve stems at any desired relative position of the diaphragm 36.

The apparatus shown and described provides for three steps of control, which may be designated as apilot fire, an intermediate or moderate fire, and a maximum or intense fire, but it will be understood that, if desired, a greater number of steps may be provided by increasing the number of pistons in the master controller, corresponding with the number of steps desired.

Having now described our invention, what we claim as new, and desire to secure by Letters Patent, is

1. The combination With a steam boiler and furnace, of mechanism for conveying pulverized fuel to a distribution point, a conduit for supplying fluid under pressure at the distribution point for conveying the fuel to the furnace, a conduit for supplying air to'the furnace for combustion of fuel, means for regulating the speed of said mechanism, and the rate of flow of the distributing medium and air for combustion through said conduits, and a controlling device operated according to variations in pressure in the smoke stack for governing the operation of said regulating means.

2. The combination with a steam boiler and furnace, of mechanism for conveying pulverized fuel to a distribution point, a conduit for supplying fluid under pressure at the distribution point for conveying the fuel to the furnace, a conduit for supplying air to the furnace for combustion of fuel, means for regulating the speed of said mechanism, and the rate of flow of the distributing medium and air for combustion through said conduits, and a controlling device adapted to be operated according to varia tions in the furnace stack draft pressure or according to variations in steam pressure in movable abutment operated according to variations in steam pressure in the boiler for serially operating said valves.

4. The combination with a steam boiler, of an apparatus for controlling the combustion of fuel for heating said boiler, including an operating member and a controller therefor, said controller comprising pistons operatively connected to said member, each piston being responsive to a difierential of pressures on its opposite sides for operating said member, a. valve for controlling the differential pressure on each piston, and a movable abutment operatively connected to said valve and responsive to variations in the steam pressure in the boiler for successively operating said valves.

5. The combination with a steam boiler, of an apparatus for controlling the combustion of fuel for heating said boiler including an operating member and a controller therefor, said controller comprising pistons operatively connected to said member, each piston being responsive to a differential of pressures on its opposite sides for operating said member,-a valve for controlling the differential pressure on each piston, a cross arm having means for operating said valves successively, and a movable abutment responsive to variations in steam pressure in the boiler for operating said cross arm.

'6. The combination with a steam boiler, of an apparatus for controlling the combustion of fuel for heating the boiler, including an operating member and a controller therefor, said controller comprisingv a piston operatively connected to said member and responsive to a differential of pressures on its opposite sides for operating said member, a valve for controlling the differential pressures on said piston, a movable abutment responsive to variations in the steam boiler pressure for operating said valve, and an auxiiiary means responsive to variations in pressure in the smoke stack for also creating a difierential pressure on said piston.

7. The combination with a steam boiler, of an apparatus for controlling the burning of fuel for heating the boiler, comprising a device for su plying fuel, a conduit through which a fiuid pressure medium for distributing the fuel is supplied, a valve for regulating the supply of fuel distributing medium through said conduit, a conduit for the rheostat, the stack damper, and the draft supplying air to the fire,'a valvefor regudoor, and a controller governed by steam lating the supply ofair through said conboiler pressure for operating said shaft. 10 duit, an electric motor for operating said In testimony whereof We have hereunto 5 device, a rheostatfor controlling the speed set ourhands.

of said motor, a stack damper, a draft door, SIDNEY G. DOWN. a shaft operatively connected to said valves, CARLTON D. STEWART. 

